In the years since the fall of communism, as the social fabric of Russia fell apart, street children became a common sight in Moscow and St Petersburg. Like the homeless in London, they were both ever present and subtly invisible - a backdrop to city life; an irritating intrusion on the process of simply getting on with things. But one of these Moscow street kids was different. He was actually to find the visibility that had so long been denied to him.

In 1996, Ivan Mishukov left home. He was four years old. Ivan's mother could not cope with him or with her alcoholic boyfriend, so the little boy decided that life on the streets was better than the chaos of their apartment; and just as Moscow has its homeless, so it has its wild dogs, an inevitable consequence of the inability to create facilities for the city's many strays. Out on the streets, Ivan began to beg, but gave a portion of the food he cadged each time to one particular pack of dogs. The dogs grew to trust him; befriended him; and, finally, took him on as their pack leader.

The relationship worked perfectly, far better than anything Ivan had known among his fellow humans. He begged for food, and shared it with his pack. In return, he slept with them in the long winter nights of deep darkness, when the temperatures plummeted. The heat of the animals kept him warm and alive, despite the snow, the bitter cold; and if anyone should try to molest him or thieve from him, the dogs were there on hand to attack them.

The police came to know of Ivan's life, but could not wrest him from the streets. Three times he escaped his would-be captors, fleeing as the dogs savagely defended their leader. Eventually the police managed to separate the pack from Ivan by laying bait for the animals inside a restaurant kitchen. Deprived of his guard dogs, the savagely snarling boy was quickly trapped.

He had been living on the street for two years. Yet, as he had spent four years within a human family, he could talk perfectly well. After a brief spell in the Reutov children's shelter, Ivan started school. He appears to be just like any other Moscow child. Yet it is said that, at night, he dreams of dogs.

When his story was released in July 1998, Ivan's case was extraordinary enough to gain the attention of the world's press. Yet his experience is not unique. Over the past 400 years, several such children have been discovered and brought back into civilised life. The fascination with the wild child goes back a long way, and Ivan's story also has many counterparts in the myths of antiquity. Again and again we find legendary tales of the hero abandoned at birth and brought up by animals or in isolation: the wild education of Cyrus; the riverside abandonment of Moses; the infancy of Semiramis, founder of Babylon, fostered by birds; the story of Oedipus, lamed and left in the wilderness of Kithairon; the childhood of the twins, Amphion and Zethos, forsaken on a mountainside; the exposure of Paris on the slopes of Mount Ida, where for five days he was suckled by a bear; the story of Tyro, and Neleus and Pelias; the infant Aleas fed by a doe.

Often these heroes go on to become the founders of cities - such as Amphion, whose music charmed the very stones to build by themselves the walls of Thebes.

The most famous of all Ivan's mythical progenitors, however, are Romulus and Remus, the founders of Rome. Their story offers us a template that would fit equally well many of these other versions of the myth. The twins' mother was Rhea Silvia, daughter of Numitor, once the King of Alba Longa, but by then deposed by Amulius, his wicked brother. In order to prevent his niece, Rhea Silvia, from having offspring and so continuing Numitor's lineage, Amulius forced her to become a vestal virgin. One night, however, a ghostly and very large phallus appeared in the vestals' temple and impregnated Rhea. Amulius was maddened with rage, but Rhea protested that it was the god Mars who was responsible for her pregnancy. On her giving birth to twin sons, Amulius ordered that the infants be exposed. They were taken to the river Tiber, where they were left to "the mercy of fortune", as Thomas North's 16th-century translation of Plutarch puts it. Death seemed imminent, but help came from an unexpected quarter: a she-wolf suckled the young infants, and a woodpecker fetched food for them. The twins lived on in this way until a shepherd, named Faustulus, discovered them.

Faustulus and his wife, Acca Larentia, brought up the children, who turned out to be noble, virile and courageous. The twins grew up to lead a band of outlaws who raided the countryside, until eventually their true identity was discovered. They overthrew Amulius and restored Numitor, their grandfather, to the throne of Alba Longa. The twins then set out to found a city of their own.

Restorations and substitutions are at the very heart of the Romulus and Remus story: brothers take the rightful place of others, foster parents bring up other people's children, the god Mars stands in for a human suitor. Yet the crucial substitution occurs when the she-wolf saves the lost children. In that moment, when the infants' lips close upon the she-wolf's teats, a transgressive mercy removes the harmful influence of a murderous culture. The moment is a second birth: where death is expected, succour is given, and the children are miraculously born into the order of nature. Nature's mercy admonishes humanity's unnatural cruelty: only a miracle of kindness can restore the imbalance created by human iniquity. From this experience, the city may begin over again, refounded in the building of Rome.

There are many medieval stories of wild animals coming to the rescue of such children. The folk tales of the period tell of "swan children", and in various Märchen - fairy tales - children are suckled by a hind, a goat, a lioness, a wolf, ravens, or even rats. Sometimes a beast steals a child away from its human mother; in other tales the animal rescues the child from the outrages of human cruelty. In the popular romance Octavian, another set of twin boys is nurtured by, in one case, an ape, and in the other, a lioness. In the romance of Sir Gowther, a malignant child who tears his mother's nipple while feeding from her breast voluntarily chooses the wild life, and so suffers a penance of literally living out this wildness, as he is fed from the mouths of dogs while locked in an atoning silence.

The most famous such tale, however, was that of Valentine and Orson, the twin children of outcast Bellyssant, lost in the forest. One boy, Valentine, is quickly rescued and returned to civilisation; while Orson, his brother, remains behind in the woods, where he is snatched by a bear and taken back to her lair to be fed to her cubs. There, "God that never forgeteth his frendes shewed an evydent myracle". The bear cubs, rather than devouring the baby, stroke it softly. The bear takes pity on the child and brings him up as one of her own.

The brothers separate: Valentine grows up civilised; Orson metamorphoses into that medieval bogeyman, the "wild man". Such wild men haunted the forests of medieval and renaissance romance: irrational, carnivorous, dangerous, untamed. They lived and died in the wild woods, far from the sound of church bells; hairy as demons, or sometimes leafy; always solitary; moving alone through the wilderness; sometimes snatching children or, more often, women from the beleaguered villages; marauding, angry, violent; though, if tamed, useful and loyal servants to the wandering knights given up to adventure in the trackless forests. They were invariably incapable of speech.

Valentine and Orson, the parted twins, meet, fight, recognise each other, and are reunited. Perhaps stories such as this are fables that suggest the need for a reconciliation between civilisation and the wild.

Ivan Mishukov is only the most recent real-life example of the phenomenon. In the 18th century, in woods near Hameln in Hanover, villagers came across a naked boy, whom they named Peter the Wild Boy, who went on to live for a time with George I in St James's palace. Victor of Aveyron was captured naked and mute in the woods near Lacaune in 1800. Kamala and Amala, the wolf girls of India, emerged on all fours from the jungles of Midnapore in 1921. But one of the best-documented "true" stories is that of Memmie le Blanc, the savage girl of Champagne.

Memmie was first sighted near the village of Songi one September evening in 1731. She emerged from the woods, armed with a club, in search of water. She was perhaps nine or 10 years old. Her feet were bare, but she wore a scanty dress of rags and skins, and a gourd leaf on her hair. Her face and hands were "black as a negro's", the villagers said.

After several unsuccessful attempts to catch her (she killed a guard dog with a single blow of her club), villagers tried to lure her into captivity with a pitcher of water, but she was startled and fled to the topmost branches of a tree. A canny villager then suggested that they station a woman and some children near the tree, as these would be less intimidating to the girl than the men, and that they smile to her and placidly act out a show of great friendliness. Accordingly, a woman with a child in her arms approached the tree, carrying root vegetables and two fish in her hands. She held out the food to the girl, who, pressed by hunger, came down part of the way, before taking fright and scurrying back once more to safety.

The woman calmly persisted in her gentle invitation, smiling and gesturing by laying her hand upon her breast, "as if to assure her that she loved her, and would do her no harm". The deceit was successful: the girl slipped down from her place of refuge to receive the food. The woman continued to entice her, but moved imperceptibly away, still smiling and feigning generous love. The girl followed her further from the tree; and the men who had lain in wait seized their chance to spring out from hiding and take her by force.

The girl was brought to the kitchen of the chateau of Viscount d'Epinoy. The cook was dressing some fowls for the viscount's dinner. Before anyone knew what was happening, the girl flew at the dead birds and had one of them held tight in her teeth, tearing at the raw meat. D'Epinoy arrived and, seeing what and how she was eating, ordered that she should be given an unskinned rabbit: the little girl instantly stripped its skin and devoured it.

They examined her and questioned her, but she could not understand a word of French. At first they assumed she was black. However, once they had washed her several times, they found that she was white, her apparent blackness being the result of dirt and, possibly, paint. Her hands were oddly shaped, the palms as small and neat as any little girl's, while the fingers and thumbs were curiously enlarged. Later they conjectured that this formation was the result of leaping from one tree to another, like a squirrel, her strong hands grabbing at the branches.

She wore a necklace, some pendants, and a pouch fixed to a large animal skin that was wrapped round her body and hung down round her knees. In the pouch were a club and a small knife, inscribed with strange characters, unfamiliar to everyone.

The Viscount d'Epinoy was the first of several dignitaries to take up the savage girl's cause. She was baptised in 1732 and given the name Marie-Angelique Memmie Le Blanc. She learned French rapidly over the next 10 years, lived in a series of convents, and her biography was written by two patrons and contemporaries: Madame Hequet and the Scottish lawyer James Burnett, later Lord Monboddo.

Memmie supposed that she must have been only seven or eight years of age when she had been snatched away from her own country, which she could not remember. She had, she said, been put aboard a great ship and carried off to a warm country. There they sold her into slavery, but not before they had first painted her black all over, for there were many black slaves then, taken across the sea in great ships, she added. In the hot country she was put on board another ship, and on that ship her master put her to needlework; if she did not work, he beat her. But her mistress was kind to her and would hide her away. Then the ship was wrecked and the crew took to the boat; but Memmie and a black girl were left to survive as best they could. They swam from the sinking ship, but because the black girl could not swim well, she kept herself from drowning by holding on to Memmie's foot.

At last they reached shore. They then travelled a great distance across land, moving only by night so that no one would see them, and sleeping through the day in the tops of trees. They ate roots that they had dug out from the ground, and when they could, they caught game and ate it raw with the blood still warm, like beasts of prey. She learned to imitate birdsong, for that was the only music known in her country; but she could not speak with the black girl, for neither knew the other's language. They could communicate with each other only by signs and by wild cries, such as had frightened the French villagers when Memmie was caught.

Two or three days before she had been taken, "she who is now become Mademoiselle Le Blanc, perceived a chaplet on the ground, which no doubt had been dropt by some passenger," wrote Burnett. "Whether the novelty of the object delighted her, or whether it brought to her remembrance something of the same kind that she had seen before, is not known . . ." She immediately broke into dancing.

As she was scared that her companion would take the chaplet, she reached to pick it up; but the negro girl, seeing her do so, struck her outstretched hand as hard as she could with the club that she carried. Although Memmie's hand was hurt badly, she returned the blow, striking her opponent on her brow; at this, the black girl fell to the ground bleeding, and screamed. Memmie, touched with compassion and guilt, ran in search of some frogs. When she found one, she stripped off its skin and spread it over the girl's brow to staunch the wound, binding the dressing in place with the thread from the bark of a tree. With this, the two companions wordlessly separated. The wounded girl retraced her route to the river, and the victorious one took the fateful path towards Songi.

The account of Memmie's discovery of Europe parodies and inverts the European discovery of the New World. Like Peter the Wild Boy, she presents to us the possibility of seeing ourselves as strange and new. For in Memmie's story, we find a curious inversion of the tourist's dilemma. This was not a case in which the outsider alone felt the shock of strangeness. The French were themselves perplexed and disturbed by Memmie. The inexplicable fact of her arrival seemed to endanger the security and certainty of the known. Without setting one foot outside the familiar streets of Paris, here could be had an experience just then being repeated across the Americas, Africa and the South Seas: the complex fear, shame and enticement that European colonists felt on their first contact with "savages".

While Madame Hecquet was printing her biography of Memmie, Jean-Jacques Rousseau published his seminal work, Discourse On The Origins of Inequality. Rousseau looked back with regret to the primitive origins of humankind, seeing in our simple beginnings a dignity, grace and vitality lost in sophisticated society.

Through the stories, factual and fictional, of the feral children, there emerges, perhaps, another narrative: the fragmented and haunting story of our continuing relationship with the savage image of ourselves.

· This is an edited extract from Savage Girls And Wild Boys: A History Of Feral Children by Michael Newton, published by Faber, price £12.99. To order a copy for £10.99 plus p&p, call the Guardian book service on 0870 066 7979.